Hydraulic operation of mechanism



March 12, 1946. H. scHREcK 2,396,392

HYDRAULIC OPERATION OF MECHANISM Filed May 8, 1943 4 Sheets-Sheet l i /fa nza /03 los" A TToR/VEY March 12, 1946. H. scHREcK.

HYDRAULIC OPERATION OF MECHANISM Filed May 8, 1943 4 sheets-sheet 2 cz 56pm/cf I NvENroR: HENRY SCHREQK ATTORNEY March 12, 1946. H. SCHRECK 2,396,392

HYDRAULIC OPERATION OF MECHANISM Filed May 8, 1943 4 Sheets-Sheet 3 292 294 50 f5 I 2% zer 2 9,4 283 43 @e 279 se \25/ i 66 275 7o 545g az 22,220 211. V ggf/a 2a? 199 /92 .i' 195 Iii [i4 4 A-f Y 21o za Y 5204 2,2@ 2 1904 /94 fez 205 /9/ a FIG 3 f f 97 of 8f ,59 94 00 d zoo ,60 Z i I gne ,5' /95 1 r Lz 765 9p/57 -Il en 2,59 234 27 186 z 00a 23a hi v 226 [59a i [60G 36 f 230 24 A 154@ I 224 z2 fee l 165 l 155 l INvENToR; HENRY SCHRECK 'BQ/2,4 /fw ATTORNEY 4 Sheets-Sheet 4 ,wdr-

uw Y H. SCHRECK HYDRAULIC OPERATION 0F MECHANISM Filed May 8, 1943 [NVE/vrom HENRY SCHRECK m63@ 4 /auf Arron/EY March 12, 1946.

Patented Mar. 12, 1946 HYDRAULIC OPERATION 0F MECHANISM Henry Schreck, Beloit. Wis., assignor to Fairbanks, Morse & Co., Chicago, Ill., a corporation of Illinois Application May 8, 1943, Serial No. 486,192

(Cl. 12S-90) 6 Claims.

This invention relatesto hydraulic operation of mechanism, such as used for the control of valves and the like, and has particular reference to an improved system of hydraulic operation of mechanism which although of general application, is especially suitable for the actuation of valves of internal combustion engines.

A particular object of the invention resides in an improved system of fluid actuation of mechanism, such as fluid control valves, which aiords smooth, efcient and relatively silent valve actuation, and which when utilized in the operation of engine kfuel and air control valves, results in improved engine operation.

A primary objective of the present invention is attained in an improved hydraulic actuator for a reciprocating element, useful as for engine valve operation, and in which provision is made by completely hydraulic control for varying the timing, the extent and the duration of hydraulic impulse; according to one useful application of this system and improved structure thereof the invention objectively provides for variation by means of a single control, in-tirning, duration and lift of opening of a puppet valve for an internal combustion engine.

Another important objective of the invention is attained in an improved combination of a plurality of hydraulic impulsing assemblies of control means operating. entirely hydraulically and in the hydraulic system for readily attaining a diierential control of a plurality of valves, for example, responsively to varying load conditions in an internal combustion engine.

A still further important objective of the invention is attained in an improved arrangement ment of the invention as illustrated by the accompanying drawings.

While as hereinabove indicated, the presently l improved hydraulic actuating system is of genin a complete hydraulic actuator assembly, for' effecting a convenient manual control of surge conditions in the system, whereby to assure at all times and under all conditions exactitude of timing, elimination` of unwanted noise, and general smoothness and eiliciency of valve operation.

A further object resides in the provision of a relatively compact, structurally simple, hydraulic actuating system of the character indicated, which includes iiuid pump means regulated in respect to fluid pressure output, and hydraulically operated valve means of improved Character, which are suitable for association with an internal combustion engine to control the valves thereof.

Other objects and advantages of the presently improved system of hydraulic actuation of valves and the like, will appear readily from the following description of a preferred exemplary embodieral application, it is preferred to illustrate and describe the` system herein in association with an internal combustion engine having valves of fluid actuated type, wherein the system is in direct control of the operation of these valves. Accordingly, in the drawings;

Fig. 1 is an assembly view in elevation, of an engine shown in part only, with certain parts broken away for clearness, and incorporating the hydraulic valve actuating system of the present invention; f

Fig. 2 is an enlarged vertical section through the fuel and air control valves of the system, illustrating an improved valve and valveactuating assembly;

Fig. 3 is an enlarged section taken vertically through a fluid pump, and through a manually controlled valve device associated therewith, the pump and valve shown being operatively associated with the engine air control valve of Fig. 2;

Fig. 4 is a fragmentary sectional view of the pump adapted for operative association with the engine fuel control valve as appears in Fig. 2;

Fig. 5 is a planar development of a control element carried by or formed as a part of a special pump or impulsing plunger, such as shown by Fig. 3;

Fig. 6 is a planar development, similar in nature torthat of Fig. 5, but showing, in plan, A

the nature and relation of liquid control margins of the control element carried by the plunger, in the structure of Fig. 4;

Fig. 7 is an enlarged sectional view as taken transversely through a fluid pump, along the line 'lin Fig. l, showing a pump control feature thereof, and

Fig. 8 illustrates graphically by curves, the areas of valve opening attained in the cycle of impulsing valve operation under given conditions of engine operation.

Referring first to Fig. l of the drawings, there is illustrated an internal combustion engine generally designated by the numeral I0, including in the portion thereof shown, a cylinder assembly Il extending above the engine crankcase (not shown) and an engine actuated governor device M of suitable type and construction, having an operating arm I5 '(shown in broken outline) connected by a link IB (alsoin broken outline) to a control arm 18 mounted on a frame I9 for swinging movement about a pivot 26. 'I'he function of the governor assembly in the present valve actuating system will appear hereinafter. Although not necessary to be described in detail, it will be understood that governor I4 is engine driven, as by suitable gearing or chain drive connections. The engine illustrated is of the same general type as that forming the subject matter of application led July 1l, 1941, Serial Number 401,884, by this' applicant.

Mounted on the engine camshaft casing shown in its upper portion 22, and adjacent the cylinder |I, are a pair of fluid pumps 23 and 24 of reciprocating plunger type as indicated by Figs. 3 and 4, each of which is cam-actuated preferably from the engine camshaft shown at 26, within the casing 22. Although not shown, the camshaft is engine driven, as by suitable gearing or other connection. The pumps are supplied with a suitable hydraulic operating fluid, and may be supplied .from a common source provided as by a tank assembly indicated generally at 21, through a supply header 28 connected to each of the pumps, and at one end to the tank 21 by a feed pipe 30. The opposite end of header 28 is connected to tank 21 by a return pipe 32.' There is thus provided a closed uid system, with fluid circulation therein maintained during engine operation, by the suction and uid by-pass functions of theseveral pumps in the instance where the supply vsource 21 is provided by a tank, as will appear more fully hereinafter, or by the pressure circulation eifect of the source 21 when constituted in part by a suitable pump 29, As illustrated in Fig. 1, the pump 29 which may be engine driven through the gearing 3| and drive shaft 33 operatively connected (not shown) with a rotating part of the engine, as for example. the camshaft 26, receives fluid from a suitable source (not s-hown) through conduit 34, and delivers the fluid under pressure, through conduit 36 leading preferably into the upper end of tank 21. It may be noted here that in the event a tank alone is employed as the fluid source 21 of the system, such tank may and preferably will be somewhat elevated relative to the header 28, so as to provide a desired initial duid-pressure head in the header,

Within the cylinder head 35 of cylinder I I, are a pair of valves 38 and 39 (Fig. 2) the valve 38 serving for example, as a control for meteringair in the cylinder, while the adjacent valve 39 controls fuel admission. By way of preliminary reference to overall function, it may be noted that these valves are actuated respectively, by hydraulic valve-motors 4|) and 4| suitably mounted on the cylinder head as shown. Actuating iluid is delivered to the air valve operating motor 40 by the pump 23 through a conduit connection 42 and a valve device 43 hereinafter to be described, and arranged by preference, at the discharge end 44 of the pump. In a similar manner, actuating uid for the fuel valve operating motor 4|, is delivered by pump 24 through a conduit connection 46 and a valve device 41 similar to the valve device 43, at the discharge end 48 of the pump.

Since certain of the valve motors, pumps, valves and related elements are illustrated as vertically mounted, some of the parts are hereinafter sometimes referred to as upper or lower elements, but without restriction as to necessary positions of mounting or usage.

Fig, 2 illustrates in vertical section, the fuel and' air valves of the engine and the hydraulic actuating motors therefor, as provided for the cylinder shown. Describing first the air valve 38 and its operating motor 46, the valve 38 which includes a valve head 5U and valve stem 5|, is arranged in the cylinder head so that the valve head 56controls the opening and closing of the cylinder air port 52 between the cylinder chamber shown in its upper portion at 54, and the air chamber 55 formed in the cylinder head, the latter chamber being in communication with an air conduit (not shown). The valve stem i5I is journalled for reciprocable movement, by a sleeve or bushing member 56 fixed in the cylinder head 35, the valve stem projecting therebeyond for operative association with the motor 40 and a valveclosure spring 58. As appears, the valve stem below its upper end 59, is circumferentially recessed at 66, for the reception of the internal ange 62 of a tapered split collar 63. The split collar in turn, is engaged by an internally tapered annular ring 64 having an outstanding circular flange 66. Through the collar S3 and the wedged connection of thev ring 64 therewith, the ring is thus fixed to the valve stem, The spring 58 has its upper end bearing against the ring flange 65, and its lower end abutting a hanged portion 61 of the sleeve member 56, being thus arranged to load or bias the valve stem 5| in the upward direction for seating the valve head 59 to close the air port 52. The valve mo-tor 40 includes a casing 68 having a mounting iiange 10 engaging the cylinder head 35 and secured thereto, as by the studs 1| (Fig. 1), the casing providing a lower chamber 12 open at its lower end 14, for receiving the upper or outermost portions of the valve stem '5I and spring 58. The chamber 12 may be open to the atmosphere as at 13, in order to prevent air entrapment in the chamber. Casing 68 further has an upper chamber 16, open at the top and separated from the lower casing chamber 12 by a transverse wall 18. The wall 1S is apertured centrally thereof at 19, to receive therethrough the lower end portion Se of a cylinder member 82 seated in the upper chamber 16. The member 32 provides a cylinder bore 83 for a vertically movable piston 84 having its lower end 66 normally engaging the upper end 5S of the valve stem 5|. The piston has a pressure head 81 exposed in an enlarged cylinder pressure chamber 88 at the upper end of the bore 33, and is provided with a stop element or pin-like member 9| extending beyond the head 31 and through a pin bore 92 formed in the head section 94 of the cylinder member 82. Fluid-pressure admission to the cylinder chamber 88,. is effected through radial passages 95 in the cylinder member, communicating with an external annular channel 95 therein, which in the assembly positionment of the cylinder, aligns with a threaded passage 98 through the wall of the casing 6B. Communicating with the passage 98 is the iiuid conduit 42 leading from the pump unit' 23 (Fig, l) connection of the conduit in fluid flow association with the passage 98 being made in a fluid-tight manner, as by a detachable coupling element threadedly received in passage 98, as shown.

The cylinder 82 is retained in assembly with the casing 68 by a removable cap element I6?.

` suitably secured to the upper end of the casing,

as by the studs or bolts |63, the lower end |64 of the cap projecting within the upper casing chamber 16 for lassembly abutment with an annular shoulder |65 on the cylinder head portion 94, formed by reducing the cylinder head as shown at |66. A suitable gasket |08 of a compressible character, is by preference, interposed between the cap and cylinder shoulder to effect a fluid-tight seal at this zone.

The reduced cylinder head portion |06 is thereby adapted for reception in the cap |02, to cooperate therewith in defining a chamber |09 within the cap |02 for a purpose which will appear. The upper end IIO of piston stop pin 9| is exposed in chamber |09 for abutment with an adjusting screw H2 extending through the top of the cap |022. It will now appearthat through the screw SI2 and pin 9|, the upward extent of piston movement and hence of the valve stem 5|, may be controlled to any desired degree, as for effecting a condition wherein, when the valve 50 is fully closed; the valve stem 5| and piston 84 will be in substantial engagement as illustrated, whereby to avoid, or at most have but an irreducible minimum of initial lost motion of the piston relative to the valve stem.

In the operation of the valve as thus far described, admission of fluid under pressure into the pressure chamber 88, will effect a downward displacement of piston 84 and a corresponding downward movement of the valve stem 5| and valve head 50, to open the port 52 as for proper control of air for combustion in the engine cylinder chamber 54, Upon release of fluid pressure in motor chamber 88, the valve return spring 58 then restores the valve 50 to port-closing position, and returns the piston 84 and stop element 9| to an initial position wherein the stop pin 9|' is substantially in abutment with the adjusting screw IIZ.

An important feature of the presently improved valve assembly is found in the present provisions for removing air and other gases from the motor actuating fluid upon its admission under pressure to the motor chamber B8. The piston stop pin 9| which extends through cylinder head bore 92, is given a predetermined degree of clearance therein sufiicient to permit pressure-flow of gases and a minimum uuantity of fluid entrapped in such gases, from the pressure chamber 88, between and along the opposed surfaces of the bore 92 and pin 9| therein, and into the upper chamber |09 heretofore described, for ultimate discharge therefrom. Such clearance longitudinally between pin 9| and bore 92 is indicated in Fig. 2 by the legend Clearance In order to assure delivery of gases into -the leakage or vent passage through bore 92 as above described, the uppermost or top wall Ill! of the pressure chamber 89, is inclined upwardly and convergently toward the vertical axis of the cylinder head bore 92, to terminate in the circular margin H5 defining the lower end of the bore 92. By reason of the predetermined clearance of the pin 9| .in bore 92, the margin IIS cooperates with the. adjacent opposed surface of the pin to form an inlet port-opening for the leakage passage through the bore 9".. Thus as air and other gases in the fluid under pressure in chamber 88, collect in the upper zone of the chamber, such air and gases will be concentrated at the leakage port by reason of the upward convergence of the chamber top wall I I4, for pressure discharge into and along the clearance passage in bore 92.

Such air and other gases together with a small amount of fluid, which thus attain and accumulate in the cap chamber |09, may be readily removed therefrom in any suitable manner. As presently preferred, a discharge opening IIB is provided through a wall portion of the cap element |02 near the upper zone of the chamber |09, and is connected to the return conduit 32 of the fluid system heretofore described, by a suitable conduit (not shown). Thus fluid and gases received under pressure in the cap chamber |09, may readily pass into conduit 32 for delivery to the tank or pump unit 21, wherein the gases may be vented to atmosphere in any suitable manner not presently illustrated.

The valve and actuating motor assembly 39, 4I controlling fuel admission to the engine cylinder is in all important respects as to structure and function, broadly similar to the above described air control valve assembly 38, 00. Hence in the following description thereof, those parts which correspond to the similar parts of the air valve assembly, will be designated by the same reference numerals differentiated however, by the letter suffix a.

Valve 39 includes a valve head |39 and vertically extending valve stem ISE, the latter being journalled in a sleeve 55a which is here formed as a part of a cylinder head insert member i332, providing a fuel-receiving chamber i3d supplied with fuel from a suitable source not shown, and having its lower end |35 presented to the engine cylinder chamber 59. A port opening |35 and port passage |38 formed in the lower end portion of member |32, serve to communicate the fuel supply chamber i34- with the cylinder chamber 54. and the valve head |30 as shown,` is arranged to control the port |36. The engine cylinder head 35 is recessed as at |39, for receiving the insert member |32, and the latter is retained therein, through the lower projecting end |40 of the valve motor casing 68a which engages the upper end |42 of member |32 through a sealing gasket |43, the casing 90a in turn being secured to the cylinder head 35 as by the casing flange ma and studs 'II a. The valve stem I3! vertically movable in sleeve a is sealed against fuel leakage upwardly therealong by a plurality of annular grooves IM of suitable character, and supports at its upper end portion 59a a split collar 53a engaged in the stem groove 50a. The collar is tapered on its external surface as shown, and

supports thereon the correspondingly tapered ring 64a. A ange 66d on ring 50a, provides a bearing abutment for the upper end of valve-closing spring 58a, the spring thus loading the valve stem I3 for urging the same upwardly to seat the valve head |39 at the fuel inlet port |33.

The casing 68a for the valve motor 0|, provides the lower chamber 19a open at its lower end 10o, for receiving the upper portions of the valve stem I3! and spring 58a, and. open to the atmosphere,

as through a vent opening i3d. An upper chamber 15a formed by the easing 58a and separated from the lower chamber therein by the transverse wall 18a. has mounted therein a cylinder member 82a which differs from the cylinder member S2 of valve motor t0 only in that the diameter of the cylinder bore 83a is somewhat greater. The lower end a of cylinder 82a is projected downwardly through an opening 19a in the casing wall 18a., in order that the lower end I 40 of a piston |41 may be exposed in the lower casing chamber 12a, for abutting engagement through a piston element hereinafter referred to, with the upper end 59a of the valve stem I3I The piston 14'! being larger in diameter than the piston 80 of valve motor is preferably of hollow construction providingT en integral piston head |08, and being open at its lower end |46. The latter open end of the piston is closed by a wall insert 15| which is formed to provide an abutment projection |52 for engaging the valve stem I3I, as shown. The piston head |48 has its external pressure surface lll?,V exposed in an enlarged cylinder pressure chamber Sa, and is provided with a stop pin 9 la which projects therebeyond through a bore 92a in thecylinder head 94a. As in the instance of valve motor dll, Huid-pressure communication with the cylinder chamber 88a, is effected through radial passages 95a in cylinder 82a, external annular cylinder wall channel 96a, and casing passage 98a in communication with the fluid conduit l leading from pump unit 2l?. (Fig. 1). Assembly connection oi the conduit d may be made as by a fluid-tight coupling llllla.

Cylinder 82a is retained in casing 520, by removable cap member |l2a which in turn is suitably secured to the upper end of the casing by studs la. The lower end ldlla of cap |2221 projects within the upper casing chamber a for assembly engagement with the annular shoulder ||l5a on the cylinder head 94a, the shoulder being formed by reducing the cylinder head as at |6611.. A suitable gasket lllla interposed between the cap end Ida and the cylinder shoulder $0511. serves to effect a fluid-tight seal in this zone. The reduced head |05a of the cylinder cooperates with the cap |92@ to form a chamber Milla within the cap, for receiving gases and leakage fluid from the pressure chamber 83a in the manner heretofore dee scribed in connection with the valve motor 52. As before, the stop pin 9 la is exposed at its upper end, in the cap chamber |99a for engagement with a positioning screw l |2a threaded in the cap. For the purposes heretofore described, the pin 9 I a is given a predetermined clearance in the pin bore 92a, as indicated in Fig. 2 by the legend Clearance, and the upper wall Hla of pressure chamber 88a is inclined upwardly and convergently toward the axis of the bore 92a, to terminate in the margin l a defining the lower open end of the pin bore. The margin l a in cooperation with the adjacent surface of pin 95a.. forms the inlet port for the leakage passage through the bore 92a. Discharge of gases and leakage nuid collecting in the head chamber |29@ is as before, effected through the return conduit 32.

It is here noted that the structure and operation of valve motor 49 associated with engine valve 32, as well as the similar motor il associated with engine valve 39, both as hereinbefore described, are fully disclosed and claimed in a copending application entitl-ed Hydraulic operating units, led May 8, 1943, by theA present applicant, and bearing Serial No. 486,194.

Turning now to the fluid pump and control valve unit 23, d3 illustrated in sectional elevation by Fig. 3, the unit which is associated with the engine air valve motor unit l@ through the conduit connection d2, includes a supporting frame or casing 5d har/ing ka mounting ange E55 near its lower open end E56, for assembly securement upon the upper wall of the camshaft casing 22 (Fig. l) as by mounting studs or bolts E53. Suitably seated within the casing ld in the upper section |59 thereof, is a cylinder member or liner |62 which may be properly positioned in the casing by a locating set screw 52. Vertically reciprocable in the cylinder liner is a pump plunger |63, by which is carried a special control element or means, preferably constituted by a head attachment |86 presently to be described, and a lower shank portion |65 projecting downwardly through an enlarged lower chamber l@ in'the casing |54. Although the control element lfl is usually formed integrally with the plunger |63,

all)

acca-sea it functions in many respects as a separate control means. The casing chamber 66 provides a cylinder for a guide sleeve 161 vertically movable therein. A frame |12 operatively supports a camfollower roller |15 which engages a cam |16 (Fig. 1) of a predetermined preferably symmetrical contour not here illustrated, lixed upon the engine camshaft 26 referred to hereinbefore. A suitable compression spring |19 having its upper end bearing against a ring element El) xed in the casing |54, and its lower end bearing against a suitable abutment (not shown) movable with frame |12, serves to urge the pump plunger, sleeve and frame 12 downwardly, for maintaining cam-following engagement of the roller |15 with the pump actuating cam E16. It may be noted that the guide sleeve |61 assures maintenance of a true vertical movement of the rod 95, roller frame E12 and roller E15., in the cam actuation of the pump plunger thereby. Although not herein illustrated, suitable provision is made to prevent angular movement of the roller frame i12 and guide piston E61 about the plunger axis.

The plunger cylinder |66 near its upper open end ld, is provided with a port opening and a passage 81 laterally through the cylinder wall, the passage opening to an annular channel |88 formed in the casing |54 about the cylinder, as shown. The casing below its upper end |99, is externally bossed at ISI, to provide for a tapped aperture |92 therethrough in communication with the casing channel |88, the tapped aperture receiving in threaded assembly therein, the threaded end |94 of a supply and by-pass fitting |95 connected into supply header 28 extending from the fluid supply cource 21 (Fig. 1).

The control element or means carried by plunger head portion |64, is adapted for controlling fluid flow through the cylinder port |86, and to this end, the upper end |98 of the control element is substantially at or planar as shown, to provide the annular port-cut-off edge |99. Suitably below the face |98, the body of the element is annularly reduced or recessed to provide a channel 290, which has fluid communication with the top surface |98, and hence with the pump displacement chamber |91y through a longitudinal groove 202 formed in the surface 2533. The upper margin 234 of the channel 290 is spiralled upwardly from a point 296 at the lower end of the `groove 222, to a point 2l1 immediate the ends of the groove, as clearly appears in Figs. 3 and 5. The spiralled margin 294 provides a port control edge for a purpose to appear, While the surface 203 intervening the control margins |99 and 2M, constitutes a port-closing valve surface, cooperating with port |86.

Seated in the casing |54 above the upper open end |84 of the plunger cylinder |611, is a member 298 which is formed with a fluid discharge pas sage 2H) vertically therethrough and in communication'with the plunger cylinder to receive liuid displaced from chamber |91, by the plunger upon its upward movement. A cap-like element 2|| forming a part of the casing 2M of valve device 43 presently to be described, serves in part through packing means 2|2 and when the casing 2|4 is secured, as by boltsl 2|S, to the upper end of the pump casing |59, to retain th'e member 298 in its assembly position. The cap 2| is centrally apertured at 2 8 for establishing communication between the discharge passage 2 9 of member 208 and the interior of the valve assembly 43.

It will appear from the foregoing description accesos of the pump mechanism, that upon rotation of the cam |16 to bring the follower roller |15 onto the low s urface (not shown) of the cam, as effected through the action of the pump spring |19, the control element |64 carried byA the pump plunger, and thus lowered in the cylinder |66, will be positioned to open the port |66 above the control edge |99, for the admission of fluid to the displacement chamber |91 above the plunger. Whereupon, further rotation of cam |16 to elevate the plunger in the cylinder through rollercam engagement, will effect initial fluid cut-off at the port |86 by the cut-olf edge |99, and then full port-closure by the valve surface 263. Concurrently, the fluid admitted to the cylinder, will be discharged under pressure through the passage 2|!) in member 208, as a result of the upward plunger displacement. During upward movement of the plunger, and depending upon the angular position of the plunger, and hence of the control element |64, in the cylinder, the lower control edge 264 thereof will uncover the port |86 to the channel 266, whereby to release fluid pressure on the discharge side of the pump and permit return flow of fluid through the groove 262, channel 266 and port |86, back into the fluid supply and b5- pass header 28. The fluid-pressure impulse function of the pump as thus indicated, will be re ferred to more fully hereinafter.

Angular orientation of the pump plunger |63 in the cylinder |64 so as to position the control element |64 and hence spiral control edge 264 relative to the port |86, serves to uncover the port at a time earlier or later in the upward fluid delivery stroke of the plunger. This may be manually adjusted, but is preferably controlled in accordance with engine operating conditions (fol` example, load) as reflected in the engine-actuated governor mechanism indicated at 4 in Fig. 1, in order toregulate thereby, the duration of opening of the air valve 38 as will appear more fully hereinafter. As presently preferred, the governor control connection to the pump plunger for determining the angular position of the latter, or more specifically the position of control element v|64 in the pump cylinder |60, includes as shown by Figs. 3 and 7, a sleeve or pinion element 222 rotatably arranged in the pump casing |54 adjacently below the pump cylinder |66, and about the intermediate section 223 of the plunger shank |65. The pinion 222 is suitably constrained against longitudinal displacement in the casing, as by a lower external shoulder 224 in engagement with the spring seating ring |80, and by an upper shoulder 226 in engagement with a ring element 221 seated in the casing |54. Connection of the pinion to the plunger shank section 223 is effected by any suitable form of securement permitting relative reciprocal movement, but preventing relative angular displacement; e. g., through one or more splines 230. The external surface of the pinion 222 is formed to provide gear teeth 23| which are engaged by the teeth 232 of a rack member 234 slidably carried in the portion 235 of casing |54 for movement in a direction normal to the pump axis. Rotation of the rack member may be prevented by a set screw 236 having its end 238 extending into a longitudinal slot 236 in the member 234. The rack 234 is by preference, a tubular member, and projected through the bore 240 thereof is a governoractuated shaft or rod 24| which has one end 242 (Fig. 1) suitably connected to the governor lever I6. As shown by Fig. 7, the rack member is adjustably positionable longitudinally of the rod 24|, as by lock-nuts 243 and 244 at the opposite ends of the member and in threaded engagement with the rod 24| as illustrated.

It will thus appear from the foregoing, that during engine operation, the governor I4, through its control arm I6 and the shaft or rod 24|, will serve to position the rack 234 according to conditions of engine function, such as speed or load, and through the rack and sleeve or pinion 222, will serve angularly to orient the plunger |63 and element |64 in the cylinder |66, such as to properly relate the spiral control edge 264 with the fluid port |86. The provision for longitudinal adjustment of the rack member 234 on the rod 24|, serves a purpose which will be described hereinafter.

The fluid pressure delivery from the pump 23 is directed through the valve device 43 presently to be described, and through conduit 42 (Fig. 1) to the pressure chamber 88 of the air valve motor 46 (Fig. 2), and upon pressure release of the fluid in chamber 68 as effected by the pump when the spiral control edge 264 of the control element |64 opens port |86, the fluid is returned through the pump and port |36 back into the supply header 28, this last fluid movement being effected as a result of the upward movement of the valve motor piston 84 under the bias of motor spring 53. The principal function of the valve device 43 is to check or cushion the return flow of fluid from the valve motor to-a predetermined extent, whereby to eliminate or minimize adverse operational effects, otherwise due to violent, undamped oscillatory surging of the fluid column between the pump and valve motor, upon the relatively sudden pressure release by the pump. Otherwise a hydralll femmine or so-calied hammer effect weuld be produced upon the air valve 38, with attendant disruption of smooth and eflicient engine operation by reason of the resulting ineffective valve-closure, even sometimes resulting, without present control features, in an unwanted valve movement. By thus regulating the fluid return flow upon pump pressure release, the fluid pressure on the motor piston 64 is relatively gradually reduced, which thereby allows the valve-closure spring 58 to effect a correspondingly gradual or attenuated closure of the valve 33 in a positive and relatively quiet manner.

As shown by Fig. 3, the valve device 43 comprises a casing 2|4 heretofore referred to, formed to provide a fluid chamber 256 open at the casing end 25|, the open end of the chamber normally being closed by a threaded head or cap element 252 sealed against fluid leakage at the opening by a suitable gasket 254. In the intermediate zone of the chamber 256, the casing is` formed to provide an annular bevelled shoulder 255 constituting a valve seat for the valve head 256 of a Valve element 258; As controlled by valve element 258, 4the seat 255 may be said Vto define the main valve port of the device. The valve element which is of substantially tubular form to provide a central longitudinal bore or passage 259, and is externally flanged' or spidered rearwardly from the valve head 256, is movable longitudinally in chamber 256, being guided in such movement by engagement of its flanges with the casing wall portion 266 of reduced diameter near the inner end 262 of the chamber. A suitable compression spring 263 bearing at one end against the cap 252, and at its opposite end against a seat 264 on the valve head 256, serves to bias the valve element inwardly of the chamber25il to seat the valve head on the chamber seat 255. The valve passage 259 at `one end 269 thereof, is outwardly bevelled to form an aperture or port-opening 251 for cooperation with the pointed end 268 of a needle-valve 219, formed of a thermally-sensitive material as an aluminum alloy, for a purpose to appear, extending axially into the chamber 259 through a guide passage 21| formed in the casing 2|4. The needle-valve passage 21| is internally threaded as at 215, to provide a threaded seat for an enlarged threaded portion 219 on the needle-valve 21|). The threaded portion 219 may be provided by a separate collar suitably secured on the needle-valve 219, or as presently preferred, may be formed as an integral part of the valve. As will appear now, the needle-valve 219 is thus mounted for longitudinal adjustment through its threaded portion 219 in the threaded seat 215, effected upon rotation of `the needle-valve element, so as to regulate the position of the portcontrolling end 268 thereof relative to the port 261 in the valve 258 when the latter is seated to close the .main valve port 255.

Packing means 282 arranged in the casing for preventing uid leakage along the needle-valve, is retained and suitably compressed therein by a gland nut or collar 283 in threaded engagement with the casing. The needle-valve is projected outwardly beyond the collar 283, and has secured thereto as by set screw 284, a hand control or knob 236 by which the needle-valve may be manually rotated for eifecting adjustment thereof. In order to indicate externally of the valve device, the relative position of the valve y tip 258 on needle-valve 219, and the port 261 controlled thereby, in any adjusted position or the needlevalve, a pointer 281 may be carried by the knob 28'6 for cooperation with an appropriate scale (not shown) on the outer end 288 of the casing. Additionally, a readily removable cover or cap 299 may be threaded onto the casing for protecting the manual control end of the needle-valve.

Fluid communication between the valve chamber 259 at the inner end 262 thereof, and the passage 2|'U in the pump head member 298, is effected by the passage 2|8 laterally in the valve casing 2|4 in the Zone of the casing element 2| I. On the opposite side of the valve 258 and near the end 25| of chamber 25), is a fluid passage 292 extending from the chamber through a valve casing extension or lateral boss 294, and communicating with this passage is one end of the conduit 42 extending to air valve motor lli (Figs. 1 and 2). Connection of the conduit to the casing extension may be eiected by a suitable coupling 295 (Fig. 1). In addition, a relief port 295 is provided in a side wall portion of the valve 253, for a purpose which will appear presently.

The pump mechanism 24 and control Valve device 41 associated with the fuel valve motor unit 4| through conduit 46, are in all important structural and functional respects, similar to the now described pump assembly 23 and valve 43, with the single exception that the plunger head |64a of pump 24, is provided with a port control edge at its upper end, as shown by the fragmentary sectional elevation of Fig. 4. For convenience, the pump elements shown by Fig. 4 and which are substantially identical with the corresponding elements of the pump illustrated by Fig. 3, are given the same reference characters with appropriate letter suix, so that the description hereinabove, may readily apply to these parts.

It is here noted that the structure and manner of `operation of the vlike control valve devices 43 and 41 are hereinabove indicated, are fully disclosed and claimed in a copending application by the present applicant, entitled Fluid flow control device, led MayS, 1943, and bearing Serial No. 486,193. A

Referring to Fig, el, the control element |S4a carried by plunger |5311 of pump 24, is formed to provide the annular channel 2990i, lower spiral control margin 29411 and a longitudinal groove 2020i between channel 20a and the planar head end portion 309. This portion is out away or otherwise suitably reduced to provide an upper 'port-control edge 30| extending from the head surface 309 downwardly in a somewhat spiralled trend, to a point 392 approximately diametrically opposite the high point 201a of the lower control edge 204a. It is .important to note here that the upper and lower control margins 39| and 204:1 extend in the `same direction about the plunger head, but the angular degree of spiral provided for the upper control edge 39| differs to a predetermined extent, from that of the lower edge 294a (see Fig. 6), for a purpose presently to appear. As may be stated generally at this point, however, the now described arrangement of `the plunger control margins provides, through angular orientation of the plunger in the cylinder as eected by the governor I4 in accordance with conditions of engine operation, for regulation of the timing of port closure at port |8611, by the upper control edg= 30|, and timing of port opening by the lower control edge 24a, both relative to the upstroke of the plunger which is of constant extent. pump unit 24 may be effected in the manner provided for the pump .unit 23, as by the cam |16a on camshaft 26 (Fig. 1).

As will be observed in Fig. l, the governor 4 is utilized to effect simultaneous control of plunger orientation in the pump devices 23-24, the governor-actuated shaft or rod 24| being extended for thisl purpose, for connection to the pump rack 234 and the similar rack (notr shown) of pump unit 24. Each of these racks .is secured upon the rod 24| in the manner hereinbefore described and as illustrated by Fig. 7 such that each may be adjustably positioned longitudinally of the rod 24|7 as for a purpose to appear.' In engines of more than one cylinder, the pump units associated with each of the additional cylinders may be similarly associated with the governor I4, as by extending the governor-actuated shaft 24| for connection to the rack members of the several pump assemblies. Or if desired in the case of multi-cylinder engines, more than one governor may be employed to effect the desired control.

Turning now to the function and method of operation of the presently described hydraulic impulse valve actuating system 'during engine operation, and considering first the fluid pump unit 23 43 and `the associated engine air valve motor unit 40, it will be observed that upon the down stroke of pump plunger |53 to open the pump port |88, fluid under the 'pressure head afforded bythe elevated supply tank 21, will flow into the cylinder IB'U above the plunger head and upwardly in the pump discharge passage 2li) to the valve chamber 25B through the passage ZIB. As the engine camshaft through cam |16 thereon, eifects upward displacement of the pump plunger |53, the control edge |99 will pass over the port |89 in the initial phase of the plunger upstroke, .to close .the port against further inlet of fluid, by the valve .forming surface .293 closely overlying the port. AS this occurs, the uid :ahead of the Actuation of the plunger |63a in' plunger will be placed under considerable pressure and will react against the valve 258 to displace the same against the bias of valve spring 263, for establishing full fluid discharge through the main port 255. rihe lluid under pressure thus passing through port 255 and about valve element 258, and thence through conduit d2 to the motor chamber Sli in valve motor dil, reacts upon piston 34 to effect downward displacement thereof and a corresponding displacement of the air valve stem 5l and valve head 5t, whereby to open the air port;

52 for communication therethrough, with the engine cylinder 5d. Following closure of the pump port |86, and as the plunger E53 continues in its upstroke, the Fluid acting on the air valve motor y piston Sd, will be placed under increasing pressure to continue downward displacement of the piston 8e against the reaction of the valve spring 5B, whereby to effect corresponding port-opening displacement of the air valve 33.

During the existence of uid pressure in the valve motor chamber 88, any air or other gases in the uid will be relieved or removed from the fluid in the manner heretofore described, as through the leak passage in bore 92, chamber itil and the relief connection to the fluid-return conduit 32 of the system.

As the pump plunger d3 approaches the limit of its upstroke, the pressure release control edge 2M of the control element ld, will uncover the port it to the channel Zoll, whereby to release the pressure in the conduit d2 and pressure chamber S8 of valve motor dll, for permitting air valve closure at the port 52. The opening of port |86 by control edge 2M will occur earlier or later in the upstroke of the plunger, depending upon the angular position of the latter in the cylinder as determined by the governor lll in the manner hereinbefore described, whereby to elect pressure release on the air valve mot-or at a period correspondingly earlier or later in the plunger upstroke. The spiral control edge Zilli as oriented in the pump cylinder, thus alords regulation of the extent of air valve opening, or valve lift, through variation in the duration of pressure ap plication upon the valve motor piston all, as efiected by relating the control edge to open the port itt and hence release the pressure on the valve, at a time earlier or later in the upstrolre oi the plunger itl-i. At the same time and by the same means, the duration of valve opening is thus determined, as will be now fully appreciated, and as graphically illustrated by Fig. 5.

Upon pressure release by the pump, the fluid in chamber 88 and conduit d2 will be released for return through valve device i3 and the pump, to the supply header 2,8, the fluid return flow being effected under the influence of valve piston Se in .its upward or return displacement by the valve closing spring 5S. By reason of the restriction or throttling of the fluid return flow by the valve device i3 as will be presently described, sudden closure of the air valve all is effectively prevented. If such were permitted, a-rapid fluctuation or surging of the fluid column between the valve motor and pump, normally would be present, which would tend to produce a fluid hammer effect upon the motor pist-on and therethrough, upon the valve 38, causing rapid partial opening and closure of the valve, with attendant disadvantages of abnormal wear of the valve parts and a noisy valve operation.

Upon pump pressure release in the system, the spring 263 of throttling Valve 43, displaces valve 258 to port-closing position v(Fig. 3) relative to the main port 255. However, when this occurs the return flow of iluid to the pump is established at a greatly reduced or attenuated rate of flow, through the valve passage 259 and the port opening 28T. The extent of throttling of fluid flow through port 261 is determined and controlled by r the adjustable needle-valve l through regulated projection of. its port control tip end 258 in the bevelled port opening 26T. Although avery small portion of the fluid returned through the Dump, normally will be by-passed about the needle-valve controlled port 251 through the small lateral opening 29S in the valve 258, the opening 296 serves as a pressurerelief expedient, to prevent pressure build-up in the fluid return flow from the valve motor chamber 88 in the event the needle valve 270 is projected inwardly inadvertently or otherwise, to an extent such as to close, or approximate closure of the port 251 by the Valve tip 268. In normal operation, the small leakage at the opening 29e may be readily compensated ior by proper adjustment of the needle-valve. The ports Ztl and 296, because small in effective area, exhibit a marked eifect in damping out line surges, particularly just after closing of the associated engine valve.

As hereinbefore indicated, the needle-valve 210 is formed from a thermally-sensitive material such as a suitable aluminum alloy, whereby to aiord automatic or self-adjustment in the return-flow throttling function of the valve device, as attained responsively to and in accordance with temperature differences in the actuating fluid employed in the system. For example, during initial or starting operation of the engine embodying the present valve-actuating system, given as one example of the utility of the hydraulic impulsing system, the valve-actuating fluid may be relatively cool or at a low temperature and hence subject to a greater flow-inertia than obtains when the fluid is at a higher temperature. The resulting thermal contraction of the needlevalve 2id effected to an extent corresponding to the existing low temperature of the actuating uid, thus affords an increased openingat the return-flow port 26? by reason of the retraction of needle-valve tip 268 from the port. The increased port-opening thereby compensates for the greater flow-inertia of the iluid throttled in its return-flow through the valve device. Nor-V mally and as a result directly or indirectly, of continued engine operation, the temperature of the actuating fluid may rise to an appreciable degree, in consequence of which the needle-valve Z'lll will undergo thermal expansion in proportion to the increase in the fluid temperature. There is thus effected in corresponding degree, an increase in fluid return-flow restriction at the port 251, by reason of the expansion projection of the needlevalve tip 268 toward and into throttling position in the Valve port 26?. Accordingly, the needle-valve control is not only manually adjustable for regulating the return-flow throttling function of the valve device d3 in accordance with given conditions of engine operation as hereinbefore indicated, but is self-adjustable in any manually controlled setting of the needlevalve, to compensate for temperature differences in the actuating iluid in the system. The latter as now will appear, serves to equalize the throttled return-flow through the 'valve device as changes occur in the temperature of the actuating huid.

During the throttled return flow of fluid from the valve motor chamber 8B, a certain portion of n the fluid normally will be returned through thel pump and port 485 to the supply header 28, under a pressure determined in part, by the pressure exerted on the fluid in chamber 33 as the valve motor piston il@ moves upwardly in its return displacement by spring S. rIhat portion of the uid attaining the header 2S is, however, under sufficient pressure to maintain fluid ow along the header and into the return pipe 32, for return to the fluid source 2'i.

The foregoing fully illustrates the cycle of hydraulic valve actuation attained by the presently improved system and apparatus, it being noted that this cycle with certain differences as between the air and fuel valve operation, occurs, in the application described, in each of the several pump and valve units. With respect to the hydraulic impulse actuation of the air valve, the extent of valve-lift and duration of Valve opening in the cycle of operation, is variable in accordance with varying conditions of engine operation, this being accomplished automatically as described, by the engine governor ifi which serves to regulate the angular position or orientation of the control means on plunger itt in the pump cylinder, for relating higher or lower zones of the pressure release control edge 2M with the pump port E86.

In regard to the fluid impulse actuation of the fuel valve unit t9-tl, angular adjustment of the pump plunger lESa to orient the control element thereon, particularly upper control edge Sill relative to they port 585er, determines the timing of port closure at port lia by the control edge. Port closure thus will occur earlier or later in the upstroke of the plunger, depending upon the angular position of the plunger and control means thereon, as controlled by the governor M in accordance with engine operating conditions. As a result, the time of initial fuel valve opening is thereby determined and controlled in relation to the earlier or later closing of the pump port lea by the control edge Sii. The lower control edge 2960, on the other hand, thereafter controls the extent of valve-lift and duration of valve opening in substantially the same manner as obtains in the air valve operation hereinabove noted, although as now appears, the extent of lift and duration of fuel valve opening may and normally will be somewhat different from the extent and duration of air valve opening, in each cycle of valve operation. Variation in the duration of fuel valve opening, upon alteration of the angular position of the control element ila, is afforded by reason of the differing degrees of angulai` spiral obtaining in the control edges 35H and Z-Ma, which thus determine the extent of plunger movement necessary to close port Ia by the upper contro-l edge elli and then open the port by the lower control edge 26M, in the upstroke of the plunger.

With respect to the governor controlled mechanism for determining angular positions of the pump plungers and contro-l elements thereon, in the several pump assemblies, the provisions herein for adjustment of the rack member 232 and the like rack member (not shown) or" pump unit 2d, longitudinally of the governor-actuated shaft 24|, constitute an important feature of the presently improved hydraulic impulsing system, In the present exemplary application of the impulsing system to the operation of cylinder valves of an internal combustion engine, it will be observed that upon securement of the rack 234 of pump unit 23 to the governor-actuated shaft 24! in one longitudinally adjusted position thereon,

the governor 4 as operated to effect a predetermined control position of its lever i3 and hence of the shaft 24H, corresponding for example, to a given condition of engine speed and load, will thus position the rack 234 to establish thereby, a predetermined angular position of the plunger control element |64 in the pump cylinder, to accord with the foregoing conditions. Consequently, in the instance of the air valve unit Sii-lil associated with the pump unit 23 under present discussion, the extent of valve-lift and duration of valve opening of the air valve 3S in each cycle of pump impulsing operation, are thus determined by the given angular orientation of thc plunger control element i613 under the above stated conditions. However, under the same conditions of engine speed and load and governor actua-tion to the control position Corresponding to the given speed and load iactors, the extent ci' air valve lift and duration of valve opening in the cycle of vpump operation, may be increased or decreased within limits, by readjustment of the rack member 231i in one direction or the other longitudinally of the governor actuated control shaft 24|.

In like manner, the pump unit 2f@ associated with the fuel valve motor unit fil, may be regulated through positional adjustment of its rack member (not shown), such that for a given condition of engine operation, there will obtain a corresponding desired lift and duration of fuel valve opening. By reason of the particular form of the control element lr'ia on the plunger of pump 26, the beginning of fuel valve opening in this instance, will be correspondingly regulated by the adjustment of the rack, as will he now appreciated.

From the foregoing, it will appear that through the rack adjustment provisions, either or both of the pump units may be regulated relative to the common governor-control therefor, to adjust the impulsing functions of the pumps for given conditions of engine operation, as in respect to speed, load or other factors, In the exemplary embodiment of the impulsing system as herein applied to the operation of engine cylinder valves, one important advantage of the provisions for rack adjust-ment on the governor shaft 2M, is that it affords relative orientation adjustments of the control elements ld and lfla in the pump units 23 and 2li, to care for fuels of different characteristics. For example, assume that the engine is operated on a `gaseous fuel of a given calorific value. The rack member of the pump 2d associated with the fuel valve motor unit di, then may be adjusted on the governor shaft isili, to predetermine the beginning of fuel valve opening, valve lift and duration oi' valve opening for a given condition, say, of engine speed and load,`

such that only that quantity of fuel of the given caloriic value, determined to be required under the foregoing conditions, will be 'admitted to the engine cylinder in each Vcycle of pump impulsing operation. At the same time, the rack 231i of pump unit 23 associated with the air valve motor unit 49, may be correspondingly adjusted so as to determine the extent of lift and duration of air valve opening, whereby to condition the air valve 33 for controlling the cylinder air required to maintain eiiicient combustion of the given fuel. Thus the system may be readily adjusted in this manner, for fuels of different characteristics and calorilic values.

With reference now to Fig. 8 which illustrates graphically by the diagrams A and B shown, the

hature of fuel and air valve operation attained by the present hydraulic valve-actuating system, the curve C in each diagram relates to the air valve 38, while the curve D in each instance relates to the fuel valve 39. Each of these curves is plotted in terms of area of valve-opening in the cycle of valve operation, as will appear. Considering the first or upper diagram A, the relative timing of fuel and air valve operation and the extent and duration of valve displacement as therein indicated, represent the events of valve operation in each cycle of hydraulic impulse actuation thereof, obtaining under given conditions of engine function, as in respect to engine speed, load and the character of fuel utilized. The form of the curves C and D and the relative timing of valve opening and valve closure shown, result from initial relative adjustment of the pump rack elements longitudinally of the governor-actuated control shaft 25E; relative adjustment of the needle-valve elements in the return-flow control valves 43 and 41, and by reason of the pump impulsing control elements IBA and lla which as fully disclosed herein, are relatively so arranged and proportioned with respect to each other, and each in respect to its associated hydraulic system, as to permit the graphically indicated regulation in relative displacement and timing of fuel and air valve operation.

The curves of diagram B are those which may obtain say under a considerably different condition of engine speed and load, and are indicative in respect to the curves of diagram A, of the relatively Wide range of control in the relative timing and displacement of fuel and air valve operation by the present hydraulic impulsing system.

The downwardly extending portion E of curve C in diagram A, which is representative of the closing displacement of the air valve 38, is determined as to the degree of slope thereof, mainly by regulation of the needle-valve 210 in the return-flow control valve 43 of the system, which thus conditions the valve for restricting the return-flow of fluid from the valve-actuating motor ill of the air valve 38, such as to retard valve closure to the extent indicated by the slope of the curve portion E. Retardation of valve closure to a greater or lesser degree through appropriate regulation of the needle-valve 21D, will result in a correspondingly more gradual or sharper slope of the curve portion E, the latter being illustrated by the relatively sharper slope of the curve portion Ein diagram B. The foregoing is applicable in like manner, to the downwardly sloped portion F of the fuel valve curve D in each of the diagrams.

The particularity of the preceding disclosure is given solely by way of illustrating merely one useful application of the invention, regarded in its broader aspects. The remarkably ne regulation possible and facilities for attaining dependable control of periodic reciprocal motion, are applicable generally to fields beyond that of the actuation of puppet valves for internal combustion engines. It will have appeared that the assembly embodies essentially a reciprocal impulsing element or plurality, such as a pump plunger, a hydraulic system and a hydraulic motor together with novel means operating entirely by hydraulic control for varying the timing of either or both the beginning and end of the impulsing movement derived, such timing being in respect to the constant or periodically operating mechanical means energizing the system, as

for example, a cam and camshaft. It will further appear that besides timing of start and iinish of the impulsing movement; the extent of such movement and its duration may similarly to the other characteristics of motion mentioned, be readily and conveniently controlled through a single control member for an individual or any plurality of related assemblies. It is further felt that as exemplified by the present disclosure, the facility for utilizing say a plurality of conventional mechanica-l energizing elements such as cams on a camshaft may, by the present improvements, be utilized through a plurality of the hydraulic systems, to effect a differential control of different reciprocally actuated elements, for example, valves. Similarly', by only minor structural differences as found for example, in the different control elements carried by the different plungers of a plurality of the hydraulic units described, not merely a differential control but in fact an even opposite regulation of different units may be readily attained in response to a given unidirectional movement of a control element, such, for example, as the rack structure under the influence of the governor of the engine as described. This feature is thought to have wide application to the control of a plurality of fluids, as for proportioning relatively exact mixtures thereof, for combustion or other purposes as may be desired.

The present invention as now fully described in connection with a preferred exemplary embodiment thereof, attains an efficient, compact and fully adjustable hydraulic impulse actuating mechanism which is particularly suited to the operation of fuel and air valves of internal combustion engines and the like, the mechanism and system of valve operation providing for positive and relatively quiet valve displacement, the latter particularly during valve closing movement.

It is to be understood of course, that While the present disclosure relates in particular to a preferred embodiment of the invention, certain changes or modifications in the several elements of the mechanism and the arrangement thereof, may be effected without departing from the spirit and full intended scope of the invention as defined by the appended claims.

I claim:

1. In a hydraulic actuating assembly for attaining a relatively rapid reciprocal movement, as of an engine valve, a plunger, means for periodically reciprocating the plunger, a reciprocal m0- tor element arranged generally to follow the reciprocal movements of the plunger, a conduit and connections, forming with the plunger and motor element when substantially liquid filled, a hydraulic column of substantially xed volume at all times, and substantially closed at all times except for periodic communication with a source of hydraulic fluid supply, and a valve element in the hydraulic column, providing alternate paths of fluid movement respectively to permit movement of fluid in the column in opposite directions, and adapted to reduce the rate of uid movement from the motor element in comparison with rate of fluid flow permitted toward the motor element.

2. In a hydraulic actuating assembly for attaining a relatively rapid reciprocal movement, as of an engine valve, a plunger, means for periodically reciprocating the plunger, a reciprocal motor element arranged generally to follow the reciprocal movements of the plunger, a conduit and connections, forming with the plunger and motor element when substantially liquid filled, a

hydraulic column of substantially xed volume at all times, and substantially closed at all times except for periodic communication with a source of hydraulic fluid supply, and a valve element in the hydraulic column, providing alternate paths of fluid movement respectively to permit movement of fluid in the column in opposite directions, and adapted to reduce the rate of fluid movement from the motor element in comparison with rate of fluid ilow permitted toward the motor element, the valve element being provided with a continuously-open passage therethrough, providing for a trickle flow' of liquid in either direction through the valve at any time.

3. The combination with a hydraulic impulse system providing a fluid conduit and a Dump of iluid impulse character, for establishing fluid pressure flow in said conduit and releasing iluid pressure in the conduit to permit fluid return to the pump, of a pressure-sensitive valve element 1;:

in said conduit, operable upon fluid pressure delivery from said pump, for establishing, at times, a full flow communication between the conduit and said pump, and means adjustable relative to said valve element and cooperable therewith upon pump release of fluid pressure in the conduit, to restrict the return flow of. fluid through the conduit to said, pump.

4. The combination with a hydraulic valve actuating system including a valve, a fluid pressure pump for applying and relieving fluid pressure on said valve, to cause valve opening and valve closure, and a conduit connection Ybetween said pump andv Valve, forming .therewith a hydraulic system closed except for fluid replenishment, of pressure-Sensitive` valve meansy in said conduit connection, operable responsively.- to fluid pressure discharge from said pump, for establishing fluid pressure flow from the pump through said temperature diierences in conduit connection and system to said valve, and adjustable means cooperable with said valve means for controlling pump release of fluid pressure on said valve.

5. The combination with a hydraulic valve actuating system providing a valve, a fluid pressure pump for applying and relieving fluid pressure on said Valve to cause valve opening and valve closure, and a conduit connection between said pump and valve, of fluid flow control means in said conduit connection, said means including a valve element having a restricted opening therein, movable from an initial position for establishing fluid pressure flow from the pump through said conduit connection to said valve, and said valve element in its initial position, serving to restrict the return flowI of fluid through said conduit connection upon pumprelease of fluid pressure on said valve, and adjustable means coacting with said restricted opening in the valve element for regulating the degree of restriction of fluid return flow through said opening.

6. The combination with a hydraulic impulse system providing a fluid conduit and a pump for alternately establishing fluid pressure ilow in said conduit and releasing fluid pressure in the conduit to permit fluid return therethrough to the pump, of a pressure-sensitive valve member in said conduit, operable in response to fluid pressure delivery by said pump, to establish fluid flow communication between the conduit and pump, and a control element cooperable withv said valve. member upon pump release of uid pressure in the. conduit,r to restrict return ow of uid to the pump, said control element being cf a thermallysensitive material and adaped to equalize the return ilow of lluid to the pump, in response to. the uid in the system. HENRY SCHRECK. 

